The present specification relates generally to the field of displays. More specifically, the specification relates to virtual displays.
Virtual displays can provide information that is viewable in virtual space for a user of equipment, such as aircraft, ships, boats, naval craft, medical equipment, robotic equipment, remote vehicles, unmanned vehicle systems (UVSs), training simulators, entertainment systems, military equipment, land vehicles, etc. The information can include navigation parameters, guidance parameters, equipment parameters, location information, video information, remote views, symbology, etc.
Virtual displays can utilize Head Mounted Displays (HMDs) (e.g., helmet mounted displays and head worn displays) to provide images to an operator or user (e.g., a pilot in a cockpit). In aircraft applications, HMDs generally include visors, combiners, optical projection elements, an image source, and a head orientation sensor. The image source provides an image which is projected to a combiner to provide a collimated image to the pilot. The image can include enhanced vision images, targeting data, flight instrument data, synthetic vision images, head up display (HUD) data, etc.
Conventional HMDs and HUDs require bore sight accuracy. Conventional HUDs typically position the combiner and the projector for bore sight accuracy at installation. The conventional HUDs require a fixed combiner and projector, each being fixed to a single calibrated position in the cockpit. HMDs, such as those used on modern fighters, use a complex head orientation sensor to coordinate the image provided to the pilot with respect to the view within and outside the cockpit. However, complex orientation sensors are expensive, tolerance limited, bulky, require calibration, and can be inaccurate.
HMDs and HUDs have used wave guides with diffraction gratings. The gratings can be switchable Bragg gratings. Certain HMD and HUD systems (such as those described in the applications incorporated herein by reference) use an optical waveguide configured as a flat plat glass with diffraction gratings. The flat plate of glass serves as a waveguide and a combiner. Light from a single LED illuminated LCD micro display is collimated and provided in the forward field of view of the pilot as an expanded view of the image on the micro display. Generally, the expanded view image is limited to the information provided on the single micro display.
Thus, there is a need for a low cost, lightweight virtual display system capable of displaying images from more than one image source. There is also a need for a multiple display virtual display system. There is further a need for HUD or HMD system and method that can be easily integrated in the design of a cockpit without requiring extra display space. There is further a need for a HUD or HMD that can provide multiple sources of information on a combiner. There is also a need for a virtual display system and method that is optimized for providing different types of information suitable for use in a cockpit environment. Yet further, there is a need for an HMD or HUD system that displays types of information in positions that are appropriate for the particular type of information. Further still, there is a need for an HMD which does not require head tracking.
Accordingly, it would be desirable to provide a display system and/or method that provides one or more of these or other advantageous features. Other features or advantages will be made apparent in the present specification. The teachings disclosed extend to those embodiments which fall within the scope of the appended claims, regardless of whether they accomplish one or more of the aforementioned advantages or features.